System and method for increasing the depth of focus of the human eye

ABSTRACT

A method and apparatus for increasing the depth of focus of the human eye is comprised of a lens body, an optic in the lens body configured to produce light interference, and a pinhole-like optical aperture substantially in the center of the optic. The optic may be configured to produce light scattering or composed of a light reflective material. Alternatively, the optic may increase the depth of focus via a combination of light interference, light scattering, light reflection and/or light absorption. The optic may also be configured as a series of concentric circles, a weave, a pattern of particles, or a pattern of curvatures. One method involves screening a patient for an ophthalmic lens using a pinhole screening device in the lens to increase the patient&#39;s depth of focus. Another method comprises surgically implanting a mask in the patient&#39;s eye to increase the depth of focus.

RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 11/284,791, filed Nov. 22, 2005, now U.S. Pat. No. 7,404,638,which is a divisional application of U.S. patent application Ser. No.10/729,200, filed Dec. 5, 2003, now U.S. Pat. No. 6,966,648, which is adivisional of U.S. patent application Ser. No. 10/384,957, filed Mar.10, 2003, now U.S. Pat. No. 6,874,886, which is a divisional of U.S.patent application Ser. No. 09/516,258, filed Feb. 29, 2000, now U.S.Pat. No. 6,554,424, which claimed priority from provisional U.S. PatentApplication Ser. No. 60/122,001, filed Mar. 1, 1999, entitled “SCREENINGTECHNIQUES AND DEVICES USED PRIOR TO THE INSERTION OF A CORNEAL ANNULUSINLAY;” provisional U.S. Patent Application Ser. No. 60/124,345, filedMar. 15, 1999, entitled “NEW METHOD OF INCREASING THE DEPTH OF FOCUS OFTHE HUMAN EYE;” and provisional U.S. Patent Application Ser. No.60/138,110, filed Jun. 7, 1999, entitled “WOVEN ANNULAR MASK CORNEALINLAY.” This application is also a divisional application of U.S. patentapplication Ser. No. 09/516,258, filed Feb. 29, 2000, now U.S. Pat. No.6,554,424. The disclosures of all these applications are incorporatedherein, in their entirety, by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention generally relates to ophthalmic lenses and, moreparticularly, the invention relates to ophthalmic lenses for increasingthe depth of focus of the human eye.

2. Description of the Related Art

It is well-known that the depth of focus of the human eye can beincreased with the use of ophthalmic lenses with pinhole-like aperturessubstantially near the optical center of the lens. For example, U.S.Pat. No. 4,976,732 (“the '732 patent”) discloses an ophthalmic lens witha pinhole-like aperture. In the '732 patent, a mask forms thepinhole-like aperture. In one embodiment, the mask is circular in shape.When the pupil is constricted, light enters the retina through thepinhole-like aperture. When the pupil is dilated, light enters theretina through the pinhole-like aperture and the outer edges of themask.

In addition, U.S. Pat. No. 3,794,414 (“the '414 patent”) discloses acontact lens with a pinhole-like aperture. In the '414 patent, the maskforming the pinhole-like aperture has radial slits and/or scallopededges. In addition, the mask forming the pinhole-like aperture is twospaced-apart concentric circles. However, the radial slits, scallopededges and two spaced-apart concentric circles promote light diffraction,which in turn reduces the contrast of the image.

In U.S. Pat. Nos. 4,955,904, 5,245,367, 5,757,458 and 5,786,883, variousmodifications to an ophthalmic lens with a pinhole-like aperture aredisclosed. For example, the patents disclose use of an optical power forvision correction in the pinhole-like aperture, or use of an opticalpower for vision correction in the area outside the mask. In contrast,in U.S. Pat. No. 5,980,040, the mask is powered. In particular, the maskis powered to bend the light passing through the mask to impinge on theretina at a radial distance outside of the fovea. In other words, themask is powered to “defocus” the light.

In each of these patents, the mask forming the pinhole-like aperture ismade, in whole or in part, of a light absorptive material. Alight-absorptive material is a material in which light is lost as itpasses through the material, generally due to conversion of the lightinto another form of energy, e.g., heat.

SUMMARY OF THE INVENTION

In accordance with an embodiment of the invention, an ophthalmic lenscomprises a lens body, an optic located in the lens body, the opticconfigured to produce light interference, and a pinhole-like opticalaperture substantially in the center of the optic. In a furtherembodiment of the invention, the optic is configured to positivelyinterfere with parallel light reaching the optic and negativelyinterfere with diverging light reaching the optic. In addition, somediverging light may pass through the optic. In this alternate embodimentof the invention, the optic is configured to spread out the diverginglight passing through the optic.

In an alternate embodiment of the invention, an ophthalmic lenscomprises a lens body, an optic located in the lens body, the opticconfigured to produce light scattering, and a pinhole-like opticalaperture substantially in the center of the optic. In a furtherembodiment of the invention, the optic is configured to forward scatterparallel light reaching the optic and back scatter diverging lightreaching the optic.

In another alternative embodiment of the invention, an ophthalmic lenscomprises a lens body, an optic located in the lens body, the opticconfigured to produce light reflection, and a pinhole-like opticalaperture substantially in the center of the optic. In an alternateembodiment of the invention, the optic is composed, in whole or in part,of a light reflective material.

In further embodiments of the inventions, the optic may be configured asa series of concentric circles, a weave, a pattern of particles, or apattern of curvatures. In addition, the pinhole-like aperture includesan optical power for vision correction, and may have a diameter in therange of substantially 0.05 mm to substantially 5.0 mm. Further, theoptic may have an outer diameter in the range of substantially 1.0 mm tosubstantially 8.0 mm. The optic may also be composed of a materialhaving varying degrees of opacity, and the ophthalmic lens and the opticmay be composed of a bio-compatible, non-dissolving material, such aspolymethyl methacrylate or a medical polymer.

In accordance with another embodiment of the invention, a method forscreening a patient for an ophthalmic lens, the ophthalmic lens having apinhole-like optical aperture, comprises fitting each of the patient'seyes with a first contact lens, placing a mask on each of the firstcontact lens, the mask configured to produce a pinhole-like aperture ineach of the first contact lens, fitting each of the patient's eyes witha second contact lens, the second contact lens being placed over themask to hold the mask in a substantially constant position, and testingthe patient's vision.

In further embodiments of the invention, the mask may be a lightinterference mask, a light scattering mask, or a light reflective mask.The first contact lens may include an optical power for visioncorrection. In addition, each of the first and second contact lenses maybe soft contact lenses. Further, the mask for each of the patient's eyesmay have a light absorption of substantially 100%. In the alternative,the mask for each of the patient's eyes may be composed of a polarizedmaterial.

In still further embodiments of the invention, the process of testingcomprises testing the patient's acuity for distance vision under brightand dim lighting conditions, testing the patient's acuity for nearvision under bright and dim lighting conditions, and testing thepatient's contrast sensitivity under bright and dim lighting conditions.The process of testing may further comprise testing a patient's visualacuity using a night driving simulation. The night driving simulationmay include a series of objects and road signs under bright and dimlighting conditions, as well as having the patient face a simulatedoncoming automobile headlight.

In an alternate embodiment of the invention, the process of testingcomprises replacing the mask in one of the patient's eyes with a maskhaving a light L absorption of substantially 85% or less, then, ifneeded, replacing the mask in the patient's other eye with a mask havinga light absorption of substantially 85% or less. Further, the process oftesting comprises, if needed, removing the mask from one of thepatient's eyes.

In another alternate embodiment of the invention, the process of testingcomprises placing an analyzer in the spectacle plane of one of thepatient's eyes, the analyzer including a polarizing element, rotatingthe polarizing element to achieve an optimal balance of contrast andbrightness, and determining the resultant light absorption of the mask.In addition, the process of testing may include evaluating the cosmeticappearance of the mask.

In accordance with a still another embodiment of the invention, a methodfor implanting a mask in a cornea, the mask configured to increase thedepth of focus of the human eye, comprises removing the epithelialsheet, creating a depression in the Bowman's membrane, the depressionbeing of sufficient depth and width to expose the top layer of thestroma and accommodate the mask, placing the mask in the depression, andplacing the removed epithelial sheet over the mask. In a furtherembodiment of the invention, the depression may extend into the toplayer of the stroma.

In an alternate embodiment of the invention, a method for implanting amask in a cornea, the mask configured to increase the depth of focus ofthe human eye, comprises hinging open a portion of the Bowman'smembrane, creating a depression in the top layer of the stroma, thedepression being of sufficient depth and width to accommodate the mask,placing the mask in the depression, and placing the hinged Bowman'smembrane over the mask.

In another alternate embodiment of the invention, a method forimplanting a mask in a cornea, the mask configured to increase the depthof focus of the human eye, comprises creating a channel in the top layerof the stroma, the channel being in a plane parallel to the cornea'ssurface, and placing the mask in the channel. In this embodiment, themask may be threaded into the channel, or the mask may be injected intothe channel.

In still another alternate embodiment of the invention, a method forimplanting a mask in a cornea, the mask configured to increase the depthof focus of the human eye, comprises penetrating the top layer of thestroma with an injecting device, and injecting the mask into the toplayer of the stroma with the injecting device. In this embodiment, theinjecting device may be a ring of needles. In addition, the mask may bea pigment, or the mask may be composed of pieces of pigmented materialsuspended in a bio-compatible medium. The pigmented material may be madeof a medical polymer, e.g., suture material.

In one other alternate embodiment of the invention, a method forimplanting a mask in a cornea, the mask configured to increase the depthof focus of the human eye, comprises hinging open a corneal flap, thecorneal flap comprising substantially the outermost 20% of the cornea,placing the mask on the cornea, and placing the hinged corneal flap overthe mask.

In still one other alternate embodiment of the invention, a method forimplanting a mask in a cornea, the mask configured to increase the depthof focus of the human eye, comprises creating a pocket in the stroma,the pocket being of sufficient size to accommodate the mask, and-placingthe mask in the created pocket.

In further embodiments of the inventions, the mask may be a lightinterference optic, a light scattering optic, or a light reflectiveoptic. In addition, the mask may block visual aberrations. In addition,after surgery, a contact lens may be placed over at least the affectedportion of the cornea.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects and advantages of the invention will beappreciated more fully from the following further description thereofwith reference to the accompanying drawings wherein:

FIGS. 1 a and 1 b show an exemplary ophthalmic lens with an exemplaryoptic configured to produce light interference.

FIGS. 2 a and 2 b show another exemplary ophthalmic lens with anotherexemplary optic configured to produce light interference.

FIGS. 3 a and 3 b show an exemplary ophthalmic lens with an exemplaryoptic configured to produce light scattering.

FIGS. 4 a and 4 b show an exemplary ophthalmic lens with an exemplaryoptic configured to produce light reflection.

FIG. 5 shows an exemplary process for screening a patient interested inan ophthalmic lens with a pinhole-like aperture using an exemplarypinhole screening device.

FIGS. 6 a through 6 c show a mask, configured to increase the depth offocus of the human eye, inserted underneath the cornea's epitheliumsheet.

FIGS. 7 a through 7 c show a mask, configured to increase the depth offocus of the human eye, inserted beneath the cornea's Bowman's membrane.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In accordance with an embodiment of the invention, an ophthalmic lens(e.g., a contact lens, an intra ocular lens, a corneal inlay lens, etc.)increases the depth of focus of the human eye through the use of anoptic. The optic surrounds a pinhole-like optical aperture near theoptical center of the lens. The pinhole-like aperture in conjunctionwith the optic increases the depth of focus of the human eye. Inparticular, the optic increases the depth of focus of the human eyeusing light interference, light scattering, light reflection, lightabsorption and/or a combination of one or more of these properties. Anoptic configured in accordance with the various embodiments of theinvention is referred to as a Paraxial Adaptive Optic™.

FIGS. 1 a and 1 b show an exemplary ophthalmic lens with an exemplaryoptic configured to produce light interference. FIG. 1 a shows a frontview of the exemplary ophthalmic lens. FIG. 1 b shows a side view of theexemplary optic implanted in the cornea of a human eye.

Light interference is the additive process in which the amplitude of twoor more overlapping light waves is either attenuated or reinforced. Forexample, when two overlapping light waves are in-phase (the crest andtrough of one wave coincides with the crest and trough of the otherwave), then the amplitude of the resultant light wave is reinforced.This type of interference is referred to as positive interference. Incontrast, when two overlapping light waves are out-of-phase (the crestof one wave coincides with the trough of the other wave), then theamplitude of the resultant light wave is attenuated. This type ofinterference is referred to as negative interference. Of course, lightinterference also occurs between the two extremes of in-phase andout-of-phase.

As shown in FIGS. 1 a and 1 b, optic 100 is located substantially in thecenter of lens body 110. Optic 100 surrounds optical aperture 120located near the optical center of lens body 110. The specific locationof optical aperture 120 in lens body 110 varies in accordance with thepatient's eye. Specifically, optical aperture 120 is positioned in lensbody 10 to be concentric with the patient's pupil.

In operation, optical aperture 120 increases the depth of focus of thehuman eye via a “pinhole effect.” In particular, optical aperture 120increases depth of focus by limiting the light reaching the retina toplane wavefront light. In photonics, a wavefront is a surface connectingall points equidistant from a source. Plane wavefront light isrelatively parallel light, e.g., light from a distant source. It is“relatively” parallel light because, in reality, even light from adistant star is diverging light. In contrast, convex wavefront light isrelatively diverging light, e.g., light from a near source. It is easierfor the human eye to focus plane wavefront light because the crystallinelens of the human eye can focus parallel light on the retina with littleor no accommodation. In accommodation, the crystalline lens, through theaction of the ciliary muscles, thickens and, thereby, changes its degreeof curvature.

In order to achieve a useful “pinhole effect,” optical aperture 120should have a diameter in the range of substantially 0.05 millimeters(“mm”) to substantially 5.0 mm. In addition, in order to aid examinationof the retina and increase brightness when the pupil is dilated, theouter diameter of optic 100 should be in the range of substantially 1.0mm to substantially 8.0 mm. Moreover, to further improve vision, opticalaperture 120 may include an optical power for vision correction, e.g.,correction for near vision, correction for distance vision, correctionfor intermediate vision, etc. Also, the area outside optic 100 mayinclude an optical power for vision correction.

In operation, optic 100 increases the depth of focus of the human eyevia its configuration. In particular, optic 100 is configured to producelight interference via a series of concentric circles. Specifically,optic 100 is configured to reinforce relatively parallel light andattenuate relatively diverging light. When optic 100 attenuates lessthan all of the relatively diverging light, then optic 100 is furtherconfigured to spread out the diverging light that passes through optic100, i.e., weakening the diverging light passing through optic 100.Thus, because diverging light is attenuated and/or weakened, the“pinhole effect” of optical aperture 120 is increased for relativelynear objects, producing a higher contrast depth of focus image ofrelatively near objects. Moreover, because parallel light is reinforced,the “pinhole effect” of optical aperture 120 is reduced, producing abrighter image of relatively distant objects.

Optic 100 is also configured to effect the chromatic aberration of thehuman eye. The human eye's chromatic aberration, in which the size of animage appears to change when the color of the image is changed, resultsfrom the normal increase in refractive index toward the blue end of thecolor spectrum. In optic 100, the increase in refractive index is towardthe red end of the color spectrum. Thus, optic 100 may reduce or cancelthe chromatic aberration of the human eye.

Further, optic 100 is configured to meet the specific needs of thepatient. For example, a person of skill in the art understands that,among other things, the addition of concentric circles, the removal ofconcentric circles, the change in spacing between concentric circles,the varying of spacing between concentric circles, and the shape of theconcentric circles (e.g., oval, round, elliptical, etc.) would influencethe light interference properties of optic 100.

FIGS. 2 a and 2 b show another exemplary ophthalmic lens with anotherexemplary optic configured to produce light interference. In thisexemplary embodiment, optic 200 is configured to produce lightinterference via a weave. As discussed in regard to optic 100, the weavereinforces relatively parallel light and attenuates relatively diverginglight. Depending on the weave's material, the weave may also absorblight coming into contact with the weave's material. FIG. 2 a shows afront view of the exemplary ophthalmic lens. FIG. 2 b shows a side viewof the exemplary optic implanted in the cornea of a human eye.

As discussed in regard to optic 100, optic 200 is configured to meet thespecific needs of the patient. For example, a person of skill in the artunderstands that, among other things, the density of the weave wouldinfluence the light interference properties of optic 200.

FIGS. 3 a and 3 b show an exemplary ophthalmic lens with an exemplaryoptic configured to produce light scattering. FIG. 3 a shows a frontview of the exemplary ophthalmic lens. FIG. 3 b shows a side view of theexemplary optic implanted in the cornea of a human eye.

In general, light scattering is the deflection of light upon interactionwith a medium. Light is forward scattered when, upon interaction with amedium, it is deflected through angles of 90°. or less with respect tothe original direction of motion. Light is back scattered when, uponinteraction with a medium, it is deflected through angles in excess of90°. with respect to the original direction of motion.

As shown in FIGS. 3 a and 3 b, optic 300 is located substantially in thecenter of lens body 310. Optic 300 surrounds optical aperture 320located near the optical center of lens body 310. The specific locationof optical aperture 320 in lens body 310 varies in accordance with thepatient's eye. Specifically, optical aperture 320 is positioned in lensbody 310 to be concentric with the patient's pupil.

As discussed in regard to optical apertures 120 and 220, opticalaperture 320 increases the depth of focus of the human eye via a“pinhole effect.” Similarly, as discussed in regard to optics 100 and200, optic 300 increases the depth of focus of the human eye via itsconfiguration. In particular, optic 300 is configured to produce lightscattering via a pattern of particles. Specifically, optic 300 isconfigured to forward scatter relatively parallel light and back scatterrelatively diverging light. Thus, because diverging light is backscattered, the “pinhole effect” of optical aperture 320 is increased forrelatively near objects, producing a higher contrast depth of focusimage of relatively near objects. Moreover, because parallel light isforward scattered, the “pinhole effect” of optical aperture 320 isreduced, producing a brighter image of relatively distant objects.

Further, optic 300 is configured to meet the specific needs of thepatient. For example, a person of skill in the art understands that,among other things, the light absorption of the particles, the index ofrefraction of the particles, the index of refraction of the mediasurrounding the particles, the size of the particles, and the spacebetween the particles would influence the light scattering properties ofoptic 300. In addition, optic 300 may be configured to produce lightinterference, as discussed in regard to optics 100 and 200.

FIGS. 4 a and 4 b show an exemplary ophthalmic lens with an exemplaryoptic configured to produce light reflection. FIG. 4 a shows a frontview of the exemplary ophthalmic lens. FIG. 4 b shows a side view of theexemplary optic implanted in the cornea of a human eye.

Optic 400 is located substantially in the center of lens body 410. Optic400 surrounds optical aperture 420 located near the optical center oflens body 410. The specific location of optical aperture 420 in lensbody 410 varies in accordance with the patient's eye. Specifically,optical aperture 420 is positioned in lens body 410 to be concentricwith the patient's pupil.

As discussed in regard to optical apertures 120, 220 and 320, opticalaperture 420 increases the depth of focus of the human eye via a“pinhole effect.” Similarly, as discussed in regard to optics 100, 200and 300, optic 400 increases the depth of focus of the human eye via itsconfiguration. In particular, optic 400 is configured to reflect light,in whole or in part, via a pattern of curvatures. Specifically, optic400 is configured to favor transmission of the light to which theretinal rods are more sensitive, i.e., dim light and/or blue light, andto block the light to which retinal cones are more sensitive, i.e.,bright light. Thus, because bright light is blocked, the “pinholeeffect” of optical aperture 420 is increased for relatively nearobjects, producing a higher contrast depth of focus image of relativelynear objects. Moreover, because dim light and/or blue light istransmitted, the “pinhole effect” of optical aperture 420 is reduced,producing a brighter image of relatively distant objects.

In an alternate embodiment, optic 400 may be composed, in whole or inpart, of a light reflective material. A light reflective material is amaterial that, in whole or in part, reflects back light coming intocontact with the material.

Further, optic 400 may be configured to meet the specific needs of thepatient. For example, a person of skill in the art understands that,among other things, the type of material, the thickness of material, andthe curvature of material would influence the light reflectiveproperties of optic 400. In addition, optic 400 may be configured toproduce light interference and/or light scattering, as discussed inregard to optics 100, 200 and 300, respectively.

In a particular embodiment of the ophthalmic lens described in FIG. 4,optic 400 is composed of a light reflective material with a peaktransmission of substantially 550 nanometers (“nm”). A light-adaptedretina has a peak transmission at 550 nm. In contrast, a dark-adaptedretina has a peak transmission at 500 nm. Thus, an optic with a peaktransmission of substantially 550 nm filters out more light with a peaktransmission of 500 nm, i.e., bright light, than light with a peaktransmission of 550 nm, i.e., dim light. Thus, as discussed above,because bright light is blocked, the “pinhole effect” of opticalaperture 420 is increased for relatively near objects, producing ahigher contrast depth of focus image of relatively near objects.Moreover, because dim light is transmitted, the “pinhole effect” ofoptical aperture 420 is reduced, producing a brighter image ofrelatively distant objects.

Further, this particular embodiment of optic 400 may be configured tomeet the specific needs of the patient. For example, a person of skillin the art understands that, among other things, the peak transmissionof the mask may be changed, e.g., to a peak transmission of 500 nm. Inaddition, the mask may be composed of material, other than lightreflective material, which also allows the desired peak transmissions.

In alternate embodiments, the optic is composed of bio-compatible,non-dissolving material, e.g., polymethyl methacrylate or medicalpolymers. In addition, the optic may be composed, in whole or in part,of a light reflective material or, in whole or in part, of a lightabsorptive material. Further, the optic may be composed, in whole or inpart, of a material having varying degrees of opacity. The optic mayalso be configured to produce light interference, light-scattering andlight reflection, or some combination of one or more of theseproperties. Moreover, the optic may be colored to match the color of apatient's iris.

In accordance with a further embodiment of the invention, a patientinterested in an ophthalmic lens with a pinhole-like aperture isscreened using soft contact lenses and a mask, referred to as a pinholescreening device. The mask may be an optic as described in the priorart, an optic as described herein, or an optic combining one or more ofthese properties. After insertion of the pinhole screening device, thepatient's vision is tested.

FIG. 5 shows an exemplary process for screening a patient interested inan ophthalmic lens with a pinhole-like aperture using an exemplarypinhole screening device. The process begins at step 500, in which thepatient is fitted with soft contact lenses, i.e., a soft contact lens inplaced in each of the patient's eyes. If needed, the soft contact lensesmay include vision correction. Next, at step 510, a mask is placed onthe soft contact lenses. The mask should be placed concentric with thepatient's pupil. In addition, the curvature of the mask should parallelthe curvature of the patient's cornea. The process continues at step520, in which the patient is fitted with a second set of soft contactlenses, i.e., a second soft contact lens is placed over the mask in eachof the patient's eyes. The second contact lens holds the mask in asubstantially constant position. Last, at step 530, the patient's visionis tested. During testing, it is advisable to check the positioning ofthe mask to ensure it remains concentric with the patient's pupil.

A test of the patient's vision may include testing the patient's acuityfor distance vision under bright and dim lighting conditions, testingthe patient's acuity for near vision under bright and dim lightingconditions, and testing the patient's contrast sensitivity under brightand dim lighting conditions. In addition, the test may include testingthe patient's visual acuity using a night driving simulation. A nightdriving simulation may include a series of objects and road signs underbright and dim lighting conditions, as well as a simulated oncomingautomobile headlight.

The test of the patient's vision may further include changing the mask.For example, the test might first be conducted using, in each of thepatient's eyes, a mask having a light absorption of substantially 100%.If, for example, the patient experiences a sense of dimness, the mask inone of the patient's eyes may be replaced with a mask having a lightabsorption of substantially 85%. If, for example, the sense of dimnesscontinues, the mask in the patient's other eye may be replaced with amask having a light absorption of substantially 85%. Then, for example,if the sense of dimness continues, the mask may be removed from one ofthe patient's eyes.

In the alternate, the mask in one of the patient's eyes may be replacedwith a mask having a light absorption less than substantially 85%. If,for example, the patient experiences a sense of dimness with a maskhaving a light absorption of substantially 100%, then the mask in one ofthe patient's eyes may be replaced with a mask having a light absorptionof substantially 75%. If, for example, the sense of dimness continues,the mask in the patient's other eye may be replaced with a mask having alight absorption of substantially 75%. Then, for example, if the senseof dimness continues, the 75% mask may be replaced with a mask having alight absorption of substantially 50%.

As can be seen, there are numerous permutations for thoroughly screeningthe patient to find the optimal balance of contrast and brightness. Ineffect, the, mask in each of the patient's eyes is replaced, every othertime, with a mask having a different light absorption than the replacedmask. This process continues until the optimal balance of contrast andbrightness is found.

The process for changing the mask while testing the patient's visionalso includes changing from an optic as described in the prior art to anoptic as described herein. In addition, various mask configurations maybe used. For example, an optic having both light interference and lightscattering may be used, or an optic having both light reflective andlight absorptive properties may be used. Once again, the numerouspermutations allow for thoroughly screening the patient to find theoptimal balance of contrast and brightness prior to, for example, thedoctor placing a customized order or the patient undergoing invasivesurgery.

The test of the patient's vision may also include evaluating thecosmetic appearance of the mask. For example, if the patient isdissatisfied with the appearance of the mask, the mask can be replacedwith a mask of appropriate configuration colored to match the patient'siris.

In an alternate testing process, the mask placed on the soft contactlens in each of the patient's eyes is composed of a polarized material.A polarized material has a light absorption of substantially 50%. Then,an analyzer, which contains a polarized element, is used to helpcalculate the patient's optimal light absorption properties for themask. In the process, the analyzer is placed in the spectacle plane ofone of the patient's eyes and the polarized element in the analyzer isrotated until the patient experiences an optimal balance of contrast andbrightness. The process may be repeated for the patient's other eye.

Using the analyzer, the doctor may now calculate the resultant lightabsorption of the mask. If desired, a mask of similar light absorption,whether it be an optic as described in the prior art, an optic asdescribed herein, or an optic combining one or more of these properties,can now be placed between the contact lenses in each of the patient'seyes and the patient's vision tested, as described above.

In accordance with a still further embodiment of the invention, a maskis surgically implanted into the eye of a patient interested inincreasing his or her depth of focus. For example, the patient maysuffer from presbyopia, a condition in which the crystalline lens can nolonger accommodate near vision because of a loss of elasticity in thelens or a weakness in the ciliary muscle. The mask may be an optic asdescribed in the prior art, an optic as described herein, or an opticcombining one or more of these properties. Further, the mask may beconfigured to correct visual aberrations. To aid the surgeon surgicallyimplanting a mask into a patient's eye, the mask may be pre-rolled orfolded for ease of implantation.

The mask may be implanted in several locations. For example, the maskmay be implanted underneath the cornea's epithelium sheet, beneath thecornea's Bowman membrane, in the top layer of the cornea's stroma, or inthe cornea's stroma. When the mask is placed underneath the cornea'sepithelium sheet, removal of the mask requires little more than removalof the cornea's epithelium sheet.

FIGS. 6 a through 6 c show mask 600 inserted underneath epithelium sheet610. In this embodiment, the surgeon first removes epithelium sheet 610.For example, as shown in FIG. 6 a, epithelium sheet 610 may be rolledback. Then, as shown in FIG. 6 b, the surgeon creates depression 615 inBowman's member 620. Depression 615 should be of sufficient depth andwidth to both expose top layer 630 of stroma 640 and to accommodate mask600. Mask 600 is then placed in depression 615. Last, epithelium sheet610 is placed over mask 600. Over time, as shown in FIG. 6 c, epitheliumsheet 610 will grow and adhere to top layer 630 of stroma 640, as wellas mask 600 depending, of course, on the composition of mask 600. Asneeded, a contact lens may be placed over the incised cornea to protectthe mask.

FIGS. 7 a through 7 c show mask 700 inserted beneath Bowman's membrane720. In this embodiment, as shown in FIG. 7 a, the surgeon first hingesopen Bowman's member 720. Then, as shown in FIG. 7 b, the surgeoncreates depression 715 in top layer 730 of stroma 740. Depression 715should be of sufficient depth and width to accommodate mask 700. Then,mask 700 is placed in depression 715. Last, Bowman's member 720 isplaced over mask 700. Over time, as shown in FIG. 7 c, epithelium sheet710 will grow over the incised area of Bowman's member 720. As needed, acontact lens may be placed over the incised cornea to protect the mask.

In an alternate embodiment, a mask of sufficient thinness, i.e., lessthan substantially 20 microns, may be placed underneath epithelium sheet610, or beneath Bowman's member 720, without creating a depression inthe top layer of the stroma.

In an alternate method for surgically implanting a mask in the eye of apatient, the mask may be threaded into a channel created in the toplayer of the stroma. In this method, a curved channeling tool creates achannel in the top layer of the stroma, the channel being in a planeparallel to the surface of the cornea. The channeling tool eitherpierces the surface of the cornea or, in the alternative, is insertedvia a small superficial radial incision. In the alternative, a laserfocusing an ablative beam may create the channel in the top layer of thestroma. In this embodiment, the mask may be a single segment with abreak, or it may be two or more segments.

In another alternate method for surgically implanting a mask in the eyeof a patient, the mask may be injected into the top layer of the stroma.In this embodiment, an injection tool with a stop penetrates the surfaceof the cornea to the specified depth. For example, the injection toolmay be a ring of needles capable of producing a mask with a singleinjection. In the alternative, a channel may first be created in the toplayer of the stroma. Then, the injector tool may inject the mask intothe tunnel. In this embodiment, the mask may be a pigment, or it may bepieces of pigmented material suspended in a bio-compatible medium. Thepigment material may be made of a polymer or, in the alternative, madeof a suture material.

In still another alternate method for surgically implanting a mask inthe eye of a patient, the mask may be placed beneath the corneal flapcreated during keratectomy, when the outermost 20% of the cornea ishinged open.

In one still other alternate method for surgically implanting a mask inthe eye of a patient, the mask may be placed in a pocket created in thecornea's stroma.

Although various exemplary embodiments of the invention have beendisclosed, it should be apparent to those skilled in the art thatvarious changes and modifications can be made which will achieve some ofthe advantages of the invention without departing from the true scope ofthe invention. These and other obvious modifications are intended to becovered by the appended claims.

1. A method for implanting a mask in a cornea comprising an epithelialsheet, a Bowman's membrane, and a stroma, the stroma having a top layer,the method comprising: creating a flap in a portion of the cornea;creating a depression in the top layer of the stroma by completelyremoving a portion of the stroma from the cornea, the depression beingof sufficient depth and width to accommodate a mask, the mask comprisinga centrally located pinhole-like optical aperture and a structuresurrounding the aperture, the structure further having varying degreesof opacity, each of the varying degrees of opacity preventingtransmission of a substantial portion of visible light incident on thestructure; placing the mask in the depression; and placing the flap overthe mask, wherein the mask increases the depth of focus of the eye and acurvature of the cornea is not substantially changed after placing themask.
 2. The method of claim 1, wherein the mask is configured toproduce light interference.
 3. The method of claim 1, wherein the maskis configured to produce light scattering.
 4. The method of claim 1,wherein the mask is configured to produce reflection.
 5. The method ofclaim 1, wherein the mask is configured to block visual aberrations. 6.The method of claim 1, further comprising: placing a contact lens overat least a portion of the cornea until the epithelial sheet has grownover the hinged Bowman's membrane.
 7. A method for implanting anophthalmic device in a cornea comprising an epithelial sheet, a Bowman'smembrane, and a stroma, the stroma having a top layer, the methodcomprising: creating a channel in the stroma by completely removing aportion of the stroma from the cornea, the channel being in a planeparallel to the cornea's surface; and placing an ophthalmic device inthe channel, the ophthalmic device comprising a mask comprising acentrally located pinhole-like optical aperture and a structuresurrounding the aperture, the structure further having varying degreesof opacity, each of the varying degrees of opacity preventingtransmission of a substantial portion of visible light incident on thestructure, wherein the mask increases the depth of focus of the eye anda curvature of the cornea is not substantially changed after implantingthe mask.
 8. The method of claim 7, wherein the mask is configured toproduce light interference.
 9. The method of claim 7, wherein the maskis configured to produce light scattering.
 10. The method of claim 7,wherein the mask is configured to produce light reflection.
 11. Themethod of claim 7, wherein the mask is configured to block visualaberrations.
 12. The method of claim 7, further comprising threading themask into the channel.
 13. The method of claim 7, further comprisinginjecting the mask into the channel.
 14. A method for implanting a maskin a cornea, the mask configured to increase the depth of focus of thehuman eye, the cornea comprising an epithelium sheet, the methodcomprising: forming a corneal flap, the corneal flap comprisingsubstantially the outermost 20% of the cornea; placing a mask on aportion of the cornea exposed by the flap, the mask configured toprovide an optical effect whereby the depth of focus of the human eye isincreased, the mask comprising a centrally located pinhole-like opticalaperture and a structure surrounding the aperture, the structure furtherhaving varying degrees of opacity, each of the varying degrees ofopacity preventing transmission of a substantial portion of visiblelight incident on the structure; and placing the corneal flap over themask, wherein a curvature of the cornea is not substantially changedafter implanting the mask.
 15. The method of claim 14, wherein the maskis configured to produce light interference.
 16. The method of claim 14,wherein the mask is configured to produce light scattering.
 17. Themethod of claim 14, wherein the mask is configured to produce lightreflection.
 18. The method of claim 14, wherein the mask is configuredto block visual aberrations.
 19. The method of claim 14, furthercomprising: placing a contact lens over a portion of the cornea untilthe epithelial sheet has grown over the hinged corneal flap.
 20. Amethod for implanting an ophthalmic device in a cornea comprising astroma, the method comprising: creating a pocket in the stroma, thepocket being of sufficient size to accommodate an ophthalmic device, theophthalmic device comprising a mask configured to provide an opticaleffect whereby the depth of focus of the human eye is increased, themask comprising a centrally located pinhole-like optical aperture and astructure surrounding the aperture, the structure further having varyingdegrees of opacity, each of the varying degrees of opacity preventingtransmission of a substantial portion of visible light incident on thestructure; and placing the ophthalmic device in the pocket, wherein acurvature of the cornea is not substantially changed after implantingthe mask.
 21. The method of claim 20, wherein the mask is configured toproduce light interference.
 22. The method of claim 20, wherein the maskis configured to produce light scattering.
 23. The method of claim 20,wherein the mask is configured to produce light reflection.
 24. Themethod of claim 20, wherein the mask is configured to block visualaberrations.